Sonar navigation system and method

ABSTRACT

A method for pre-determining an underwater objects GPS position using a rotatable scan sonar unit linked to a boat, magnetic compass and GPS receiver. This system determines the underwater objects GPS position using the objects distance, compass heading and a GPS receiver/sonar on a boat. This system will provide real time longitude and latitude positions of underwater objects seen with sonar at a distance from a boat, and will allow for precise autopilot navigation or fixed position fishing. The system can also be used to correct for GPS errors when using previously stored waypoints positions of an object. The computer determines an objects underwater GPS position using a sonar transducer and mounted on a 360 degree movable mechanism such as a trolling motor unit, or phased array of transducers and a compass to provide heading information and formulates the objects position based on the distance and heading of the object in relation to the boats current GPS position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/528,317, filed Oct. 30, 2014, entitled “SONARNAVIGATION SYSTEM AND METHOD”, which is a continuation application ofU.S. patent application Ser. No. 13/652,438, filed Oct. 15, 2012,entitled SONAR NAVIGATION SYSTEM AND METHOD. which is a continuationapplication of U.S. patent application Ser. No. 12/537,887, filed Aug.7, 2009, entitled SONAR NAVIGATION SYSTEM AND METHOD, which claimspriority to U.S. Provisional Application No. 61/087,098, filed Aug. 7,2008 entitled SONAR NAVIGATION SYSTEM AND METHOD, all of which areincorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to sonar navigation systems. Inparticular, the present invention relates to a system and method forstoring and/or recalling coordinates of the location of underwaterobjects.

SUMMARY OF THE INVENTION

Sonar units are an important tool for fisherman on a boat. Sonar unitsprovide the user water depth, structure and fish location. The sonartransducer is used to send echo signals to determine the position of anobject and the distance to the object in the water. The sonar transducercan be mounted in several different boat locations including transommount, through hull or mounted on the lower unit of an electric trollingmotor providing multi directional pointing of the sonar echo beam. Thesonar transducer can also be mounted in different configurationsincluding, side scan, forward scan, backward scan and down scan viewingof objects in many directions in the water. With the ability to scan inmultiple directions the fisherman can cast to objects in the waterwithout getting to close to scare the fish off of these objects. Theobjects in the water may be in the form of submerged trees, rocks,boats, fish cribs and many other underwater objects. Sonar units mayalso have built in GPS receivers used to show the boats position orpreviously stored GPS waypoint positions showing structure found in thelake that fish like to hide in. Some sonar units have the ability toside scan large areas of water showing objects on the bottom of thelake, and are capable of marking these objects position based upon GPSdata stored at the time of the sonar side scanning. The user can freezethe sonar display screen and cursor to the previously viewed object onthe screen and mark or store the GPS position to use later fornavigation to the object. These side scan systems require the boat to bemoving to determine the compass heading using the GPS movement tocalculate the heading. There is a need for accurately determining anobject's GPS location if the boat is in a fixed position. Using acompass mechanically in line with the pointing direction of the sonarbeam allows for an improved method for determining the GPS position ofan object in the water. This sonar/compass configuration is mounted on a360-degree movable mechanism allowing for sweeping or scanning of alarge area while the boat is in a fixed position or moving.

As such, the present invention is directed towards an improved methodfor determining the GPS position of an object in the water up tohundreds of feet or more away from the boat. This is done with aid oflong range side scan sonar technology and by mounting a side/forwardscan sonar transducer to the lower unit of an electric trolling motor.The fisherman can then direct the sonar beam by slowly spinning/steeringthe trolling motor lower unit, scanning the lake bottom 360 degrees andhundreds of feet from the boat. This system works whether the boat ismoving or standing still. The sonar computer continuously stores compassheading, distance, and current GPS position as the lake bottom isscanned. The user can select any object (current or past view) on thescreen to determine the GPS position of that object and use the GPS datato navigate the boat or correct previously stored object positions as aform of GPS error correction. The system determines the GPS position ofobjects with the aid of a compass linked or in line with the sonartransducers scanning direction and pointing device (trolling motor) thatmay be in the form of a steerable trolling motor connected to a sonarunit. The GPS position is calculated by the sonar computer knowing thedistance the object is from the boat and the compass heading directionpointing to the object. The computer then reads the boat's currentlongitude and latitude position and formulates the object's positionusing the distance and compass direction to the object. The underwaterobject GPS position data can be used for the boat's auto pilotnavigation to guide the boat to the under water object. The user can seta distance parameter keeping the boat within a set distance away fromthe object, allowing the fisherman to cast to the object but keeping afar enough distance not to scare off the fish hiding in the object. Thesystem may also incorporate a wind detection device to properly keep theboat pointing into the wind allowing for accurate boat navigation. Theforward/side scan sonar transducer may be attached to the trolling motorlower with a removable bracket or may be manufactured permanently intothe trolling motor lower unit casing.

In another embodiment, the system may incorporate sonar using a360-degree view showing the bottom of the lake all the way around theboat. This system will control the turning speed of the sonar transducerby spinning the trolling motor steering motor at a specific rotationspeed, this speed can be measured by a feedback position sensor on themotor or by using the compass heading data measuring the degree ofmovement over time. As the transducer spins the lake bottom is scannedand the image is drawn on the sonar screen. A stand-alone motorizedmechanical spinning transducer device can also be used to replace thetrolling motor as a turning mechanism. Another configuration of a 360degree scanning system my incorporate a fixed position hull mountedphase array electronic scanning transducer with compass. This systemuses the same object detection method described above to determine GPSwaypoint positions of objects around the boat using a fixed boat mountedcompass module.

In another embodiment the compass module that is mounted in the trollingmotor may be used as a direction pointer and is coupled to the sonarunit for directing the map view image on the sonar screen. This systemwill allow the user to rotate the navigation map image 360 degreesaround showing what direction (heading) the boat should go to navigateto a GPS waypoint. The waypoint may be underwater objects like trees,rocks and other submerged objects. This method will be very helpful tothe user as it will give a good visual understanding of the currentpointing position of the trolling motor head in relation to markedwaypoints and objects in the water. Current sonar units require the boatto be moving to acquire a compass heading using GPS generated headings.This system is unique, as the trolling motor pointing heading directionwill automatically control the view of the map on the sonar without theneed for the boat to be moving to acquire a compass heading.

Other aspects of the present invention will become apparent and be morefully understood from the following detailed description andaccompanying drawings, which set forth illustrative embodiments that areindicative of some of the various ways in which the principals of theinvention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the trolling motor with a compass and atransducer.

FIG. 2 is a diagram showing the transducer coupled to a motor for 360degree positioning.

FIG. 3 is a block diagram of the sonar system.

FIG. 4 is a diagram showing various sonar display views.

DETAILED DESCRIPTION

The description that follows describes, illustrates and exemplifies oneor more particular embodiments of the present invention in accordancewith its principles. This description is not provided to limit theinvention to the embodiments described herein, but rather to explain andteach the principles of the invention in such a way to enable one ofordinary skill in the art to understand these principles and, with thatunderstanding, be able to apply them to practice not only theembodiments described herein, but also other embodiments that may cometo mind in accordance with these principles. The scope of the presentinvention is intended to cover all such embodiments that may fall withinthe scope of the appended claims, either literally or under the doctrineof equivalents.

FIG. 1 shows an electric trolling motor 1 equipped with a compass module2 built into the top of the motor head. The lower unit 2 a has a fourdirectional sonar transducers 3, 6 at the front of the lower unit. Thetransducers can send sonar beams forward, backward and the left andright to the sides. The compass 2 is in line with the transducerallowing the system to measure the heading direction of the sonar beams.This is significant in detecting the underwater objects position inrelation to the trolling motors pointing direction. This distance andheading are significant in calculating the GPS position of the object inthe water. Steering motor 4 is used to tum the motor and sweep thewaters around the boat searching for objects like submerged structure,weeds, trees, rocks, cribs, weed lines and fish.

FIG. 2 is a stand alone steering device using steering motor 7 to directthe sonar transducers 3, 6 in the desired direction scanning forunderwater objects. Compass 5 is used to know the heading an object islocated at. This device can be a stand alone pointing unit that may bemounted directly to the bottom of the boat. This eliminates the need foran electric trolling motor to position the sonar scanning beam.

FIG. 3 is a block diagram showing the trolling motor transducer 20,compass 21, and steering motor 23 connected to the sonar computer system19. The pointing direction of the trolling motor can be controlled bythe sonar computer via steering control 24 and can be used to provide360 degree circle scanning or can be controlled by an external wirelessremote control steering device 27. This external steering remote mayalso have a slow speed steering option to allow for variable speedturning of the trolling motor, to sweep the lake bottom in detail. Sonartransducer 20 is mechanically linked and in line with the compass module21 with trolling motor 22. The compass data is passed to the sonarcomputer 19 and provides heading data used to formulate the GPSlongitude and latitude of an object seen in the water by the sonar. Thetransducer 20 transmits sonar echoes in the water allowing the sonarcomputer 19 to create an image on the display that represents the lakebottom. The sonar computer also stores compass heading, GPS position anddistance information along with the sonar images. This information canbe used later to mark a waypoint location of an object. The user canselect objects on the sonar display 25 via a cursor or touch displayLCD. Once an object or location is selected on the display, the computer19 uses the previously stored information to generate the selectedobjects GPS waypoint position. To formulate the GPS longitude andlatitude of a selected point, location or object, the computer uses thecurrent or stored position of the boat via the GPS receiver 19 a and theheading/pointing direction of the sonar beam, with the distance to thatlocation/object to formulate the desired GPS longitude and latitude.

One example of a set of formulas that may be useful to generate thedesired latitude and longitude coordinates for this position is setforth below. These formulas also take into account the earth'scircumference, although this is not necessary for short distances usedwith this system, as follows:

-   -   lat asin(sin(lat 1)*cos(d)+cos(lat 1)*sin(d)*cos(tc))    -   dlon atan2(sin(tc)*sin(d)*cos(lat1),cos(d)-sin(lat 1)*sin(lat))    -   Ion mod(lon1-dlon+pi,2*pi)-pi

Where a angle; lat1/lon 1 current position; d distance; tccircumference.

Sonar computer 19 can be programmed using C or Assembly languagesoftware to process this formula, and can also use a RISC stylemicroprocessor, such as can be provided by MICROCHIP (Chandler, Ariz.)Eighteen (18) series microprocessor. The computer 19 can also use thenewly formulated GPS position of an object to correct for GPS errorsknowing that a previously marked waypoint is being viewed near thisposition. The user can correct the position of the previously storedwaypoint by highlighting the old waypoint and pressing a correctionbutton on the sonar control module 26. The user could also use thisreference object to correct all waypoints stored on the lake. Sonardisplay 25 provides images of underwater objects along with navigationalmap views. The control buttons 26 are used to program and operate thesonar system. The trolling motor seen in FIG. 3 also provides the user aview of an object while navigated towards that object. This can beaccomplished when using a forward scan transducer in conjunction withthe compass and autopilot navigation system. This navigation systemallows the sonar unit to control the navigation by reading the compassheading 12 from the trolling motor 22 and controlling the steering viathe trolling motor steering control 24. The user can also offset thecompass 12 positions to help view the object while navigating toward it.The offsetting of the compass can be manually done via a remote controldevice 27 or can be offset using the sonar controls 26.

The sonar system seen in FIG. 3 is also capable of keeping the boat at aspecified distance from the boat. The user can select how many feet theywould like the boat to be away from an object and the GPS navigationsystem will keep the boat within that distance. This will be usefulwhile fishing as the fisherman may want to stay away from an object tokeep from chasing the fish away do to the fisherman's presents.

FIG. 4 diagram shows the display views of the sonar unit 25. Displayview 8 shows a forward scan image of the boat 9 scanning the water up to200 feet. An object 10 can be seen 100 feet away from the boat 11. Thisobject is located 180 degrees in line with the head of the trollingmotor unit compass 2. This display view may be used to select anydirection of the trolling motor (forward, backward or left and rightside scan). In any one of these views the compass 21 can provide thedirection of an object in the water. The display may also providemultiple views with split view mode. Display view 13 shows a map styleimage of the lake and position of the boat 14 in relation to the objects15, 16, 17, in the water. Because the compass 21 is connected to thesonar computer 19, the view of the map in relation to the boat will betrue to the pointing position of the trolling motor head pointingdirection. This is significant as the user may want to direct the boatto a previously stored waypoint or object and can do so by simplyturning the trolling motor head into the direction of the object seen onthe display. The sonar display has the option to reposition the boat'sicon position or tum the complete display image so the pointingdirection can be seen at the top of the display. This means the displaywill rotate in relation to the pointed position. Most sonars use a GPSgenerated compass heading that does not operate when the boat isstanding still and the boat's or trolling motor's pointing position doesnot match the image on the screen. That is only one of the benefits ofhaving a compass mounted in the trolling motor head and connected to thesonar GPS system.

Sonar image 18 shows a 360 degree image of the bottom of the lake aroundthe boat. This image is drawn by the sonar precisely spinning thetransducer slowly around and creating an image. The compass heading canbe used to set the turning speed of the transducer assembly by measuringthe amount of movement in degrees over time. As the motor turns and theimage is created, the compass heading and GPS position of the boat isstored allowing for object position selecting when the scan is complete.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangements disclosed are meant to be illustrative only andnot limiting as to the scope of the invention which is to be given thefull breadth of the appended claims and any equivalent thereof.

What is claimed is:
 1. A system for controlling the position of a boat,the system comprising: a sonar transducer; a display configured todisplay sonar information corresponding to an underwater object; atrolling motor configured to mount to the boat; and a processor incommunication with the sonar transducer, display, and trolling motor,wherein the processor is configured to receive an input correspondingthe displayed underwater object, determine a relative position of thedisplayed underwater object, and control the trolling motor to hold theposition of the boat at a set distance from the displayed underwaterobject.
 2. The system of claim 1, further including a GPS navigationsystem configured to determine the current geographic location of theboat, wherein the processor is configured to use the relative positionof the displayed underwater object and the current geographic locationof the boat to control the trolling motor to hold the position of theboat at the set distance from the displayed underwater object.
 3. Thesystem of claim 1, wherein the display is further configured to receivean input from a user to define the set distance from which the positionof the boat is held.
 4. The system of claim 1, wherein the set distanceis user defined.
 5. The system of claim 1, further including a compassoperable to determine a heading of the boat, wherein the processor isconfigured to use the determined heading of the boat to determine therelative heading to the underwater object.
 6. The system of claim 1,wherein the sonar transducer is configured for attachment to thetrolling motor.
 7. The system of claim 1, further including a winddetection device in communication with the processor to determine winddirection, wherein the processor is configured to use the determinedwind direction and the relative position of the underwater object tocontrol the trolling motor to hold the position of the boat at the setdistance from the displayed underwater object.
 8. A system forcontrolling the position of a boat, the system comprising: a sonartransducer; a display configured to display sonar informationcorresponding to an underwater object; a trolling motor configured tomount to the boat; a GPS navigation system configured to determine thecurrent geographic location of the boat; and a processor incommunication with the sonar transducer, display, trolling motor, andGPS navigation system, wherein the processor is configured to receive aninput corresponding the displayed underwater object, determine arelative position of the displayed underwater object using at least thecurrent geographic location of the boat determined by the GPS navigationsystem, and control the trolling motor to hold the position of the boatat a set distance from the displayed underwater object
 9. The system ofclaim 8, wherein the display is further configured to receive an inputfrom a user to define the set distance from which the position of theboat is held.
 10. The system of claim 8, wherein the set distance isuser defined.
 11. The system of claim 8, further including a compassoperable to determine a heading of the boat, wherein the processor isconfigured to use the determined heading of the boat to determine therelative heading to the underwater object.
 12. The system of claim 8,wherein the sonar transducer is configured for attachment to thetrolling motor.
 13. The system of claim 8, further including a winddetection device in communication with the processor to determine winddirection, wherein the processor is configured to use the determinedwind direction and the relative position of the underwater object tocontrol the trolling motor to hold the position of the boat at the setdistance from the displayed underwater object.